Breath test for detection of drug metabolism

Abstract

A breath test for determining the rate of metabolism of a drug is described. First, a safe and effective amount of the drug, preferably appropriately labelled and most preferably isotopically-labelled, is administered to a subject. After a suitable time period, the exhaled breath of the subject is analyzed to determine the concentration of a metabolite. The concentration of the metabolite is then used to determine the rate of metabolism of the drug. A breath test kit is also described. Such a breath test kit would include an item or items necessary for performing at least one of the methods of determining the rate of metabolism of a drug in a subject. For example, such a breath test kit could include an isotopically-labelled drug to be administered to the subject.

What is claimed is: 
     
       1. A method for determining a therapeutic dosage regimen of a drug administered to a subject comprising the steps of: a. labeling a drug sought to be administered therapeutically to a subject with a non-radioactive isotope having a range of natural abundance and being detectable in a metabolite of said drug;   b. prior to administration of said drug to a subject, measuring a first concentration of said non-radioactive isotope in the subject's breath;   c. following said measuring step, administering said drug labeled with said non-radioactive isotope to the subject;   d. following the administering step, measuring a second concentration of said non-radioactive isotope in the subject's breath, at least one of said first and second concentrations being within the range of natural abundance of the isotope; and   e. employing the difference between said first and second concentrations to provide information as to a therapeutically acceptable dosage regimen of said drug based on metabolization of said drug by the subject.   
     
     
       2. A method according to claim 1 further comprising administering said drug to said subject in a therapeutically acceptable dosage regimen confirmed using said employing step e. 
     
     
       3. A method according to claim 1 wherein said measuring comprises the use of a measuring instrument selected from the group consisting of an infrared spectrometer and a mass spectrometer. 
     
     
       4. A method according to claim 1 wherein said non-radiactive isotope is carbon 13.